1. Field of the Invention
The present invention claims the priority under the Paris Convention based on Japanese Patent Application No. 2015-093006 (filing date: Apr. 30, 2015), the entirety of which is hereby incorporated herein by reference.
The present invention relates to a liquid antiseptic composition containing parahydroxybenzoic acid ester.
2. Description of the Related Art
Parahydroxybenzoic acid ester has excellent antibacterial activity, low toxicity, and low irritation, so that various esters are used as an antiseptic for cosmetics or the like. However, parahydroxybenzoic acid ester has extremely low solubility in water, and thus may be precipitated as crystals depending on their addition amount. Accordingly, when parahydroxybenzoic acid ester is added to a product to be antisepticized, an antiseptic composition including alcohols such as ethanol as a solubilizer has been generally used.
However, even the antiseptic composition including a solubilizer may be precipitated as crystals during storage at a low temperature, and cannot contain parahydroxybenzoic acid ester at a high concentration. A single parahydroxybenzoic acid ester may not provide a sufficient antibacterial effect, and a plurality of parahydroxybenzoic acid esters are often used concurrently in order to compensate for the antibacterial effect. However, in such an antiseptic composition, precipitation of crystals during storage at a low temperature is remarkable, and resulted preparations are handled with difficulty.
In order to improve the solubility of parahydroxybenzoic acid ester as described above, a variety of investigations has been hitherto conducted.
JP-B-S37-17994 describes an anti-mold agent comprising, as a main component, a eutectic mixture or a eutectic of two or more paraoxybenzoic acid esters. In this anti-mold agent, a plurality of paraoxybenzoic acid esters are formed into a eutectic mixture or a eutectic so that the solubility in water is considerably improved; however, the eutectic mixture or the eutectic are easily recrystallized, and it is necessary to add an emulsifier or the like in order to stably supply preparations.
JP-A-H09-124414 describes a synergistic antimicrobial agent comprising 1,2-dibromo-2,4-dicyanobutane; and at least one parahydroxybenzoic acid ester. However, such an antimicrobial agent is high in price, and is insufficient in toxicity and safety data.
JP-A-2003-252799 describes a solubilizing aid of paraoxybenzoic acids comprising an aqueous solution containing a 2-methacryloyloxyethylphosphorylcholine/butyl methacrylate copolymer. However, it is necessary that 2-methacryloyloxyethylphosphorylcholine and butyl methacrylate are subjected to radical polymerization under an inert gas atmosphere in order to obtain the copolymer, and thus such a solubilizing aid is very troublesome in production thereof, and is high in price.
Accordingly, an antiseptic composition which is inexpensive, safe and excellent in antiseptic effect, and suppresses recrystallization of parahydroxybenzoic acid ester during storage at a low temperature has been desired.